U.S. patent application number 14/011499 was filed with the patent office on 2013-12-26 for multilayer ceramic capacitor, dielectric ceramic, multilayer ceramic electronic component, and method for manufacturing multilayer ceramic capacitor.
This patent application is currently assigned to MURATA MANUFACTURING CO., LTD.. The applicant listed for this patent is MURATA MANUFACTURING CO., LTD.. Invention is credited to Koichi Banno, Taisuke Kanzaki, Masanori Nakamura, Masahiro Otsuka, Akihiro Shiota, Shoichiro Suzuki.
Application Number | 20130342958 14/011499 |
Document ID | / |
Family ID | 46879325 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130342958 |
Kind Code |
A1 |
Suzuki; Shoichiro ; et
al. |
December 26, 2013 |
MULTILAYER CERAMIC CAPACITOR, DIELECTRIC CERAMIC, MULTILAYER
CERAMIC ELECTRONIC COMPONENT, AND METHOD FOR MANUFACTURING
MULTILAYER CERAMIC CAPACITOR
Abstract
A dielectric ceramic that can be sintered at a sufficiently low
temperature and has a desired specific resistance at a high
temperature, and a multilayer ceramic electronic component (a
multilayer ceramic capacitor and the like) using the dielectric
ceramic are provided. The multilayer ceramic capacitor includes a
multilayer body having a plurality of laminated dielectric ceramic
layers, and a plurality of internal electrodes at interfaces
between the dielectric ceramic layers; and external electrodes 8
and 9 on outer surfaces of the multilayer body. The composition of
the multilayer body includes a perovskite-type compound containing
Ba and Ti (where a part of Ba may be substituted by Ca, and a part
of Ti may be substituted by Zr) as a primary ingredient, and
further includes M (where M is at least one of Cu, Zn, Li, K, and
Na) and Bi. The total content of M and Bi is equal to or greater
than 3 molar parts when the total content of Ti and Zr is 100 molar
parts. The crystal particle size of the dielectric ceramic is 30 nm
or more and 150 nm or less.
Inventors: |
Suzuki; Shoichiro;
(Nagaokakyo-shi, JP) ; Banno; Koichi;
(Nagaokakyo-shi, JP) ; Shiota; Akihiro;
(Nagaokakyo-shi, JP) ; Otsuka; Masahiro;
(Nagaokakyo-shi, JP) ; Kanzaki; Taisuke;
(Nagaokakyo-shi, JP) ; Nakamura; Masanori;
(Nagaokakyo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MURATA MANUFACTURING CO., LTD. |
Nagaokakyo-Shi |
|
JP |
|
|
Assignee: |
MURATA MANUFACTURING CO.,
LTD.
Nagaokakyo-Shi
JP
|
Family ID: |
46879325 |
Appl. No.: |
14/011499 |
Filed: |
August 27, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2012/056688 |
Mar 15, 2012 |
|
|
|
14011499 |
|
|
|
|
Current U.S.
Class: |
361/301.4 ;
156/89.14; 501/137 |
Current CPC
Class: |
C04B 35/638 20130101;
C04B 2235/44 20130101; C04B 2235/3208 20130101; B82Y 30/00
20130101; C04B 2235/785 20130101; H01G 4/1236 20130101; H01G 4/1227
20130101; C04B 2235/3203 20130101; C04B 2235/3281 20130101; C04B
35/62685 20130101; C04B 2235/3284 20130101; C04B 2235/5454
20130101; H01G 4/30 20130101; C04B 2235/3201 20130101; H01B 3/12
20130101; C04B 2235/3232 20130101; C04B 35/62675 20130101; C04B
2235/3244 20130101; C04B 2235/3215 20130101; C04B 2235/3213
20130101; C04B 35/4682 20130101; C04B 2235/3298 20130101; C04B
2235/781 20130101 |
Class at
Publication: |
361/301.4 ;
501/137; 156/89.14 |
International
Class: |
H01G 4/12 20060101
H01G004/12; H01G 4/30 20060101 H01G004/30; H01B 3/12 20060101
H01B003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2011 |
JP |
2011-060842 |
Claims
1. A multilayer ceramic capacitor comprising a multilayer body
having a plurality of laminated dielectric ceramic layers and a
plurality of internal electrodes at different interfaces between
said dielectric ceramic layers; and external electrodes on an outer
surface of said multilayer body, wherein the dielectric comprises a
perovskite-type compound containing Ba and Ti in which a part of Ba
may be substituted by Ca, and a part of Ti may be substituted by Zr
as a primary ingredient, and further includes Bi and one of M and
Q, in which M is at least one member of the group consisting of Cu,
Zn, Li, K, and Na, and Q is at least one member of the group
consisting of Ba, Ca and Sr, the total content of M, Q and Bi is
equal to or greater than 3 molar parts when the total content of Ti
and Zr is 100 molar parts, and the crystal particle size of said
dielectric is 30 nm or more and 150 nm or less.
2. The multilayer ceramic capacitor according to claim 1, wherein
the total content of M, Q, and Bi is equal to or less than 12 molar
parts when the total content of Ti and Zr is 100 molar parts.
3. A multilayer ceramic capacitor according to claim 2, wherein M
is absent.
4. A multilayer ceramic capacitor according to claim 2, wherein Q
is absent.
5. A multilayer ceramic capacitor according to claim 4, wherein
none of the Ba and Ti are substituted.
6. A multilayer ceramic capacitor according to claim 1, wherein M
is absent.
7. A multilayer ceramic capacitor according to claim 1, wherein Q
is absent.
8. A multilayer ceramic capacitor according to claim 7, wherein
none of the Ba and Ti are substituted.
9. A multilayer ceramic capacitor according to claim 2, wherein
said total content of M, Q and Bi is at a time when said dielectric
is dissolved in a solvent.
10. A multilayer ceramic capacitor according to claim 1, wherein
said total content of M, Q and Bi is at a time when said dielectric
is dissolved in a solvent.
11. A dielectric ceramic comprising a perovskite-type compound
containing Ba and Ti in which a part of Ba may be substituted by
Ca, and a part of Ti may be substituted by Zr as a primary
ingredient, and further comprising Bi and one of M and Q, wherein M
is at least one member of the group consisting of Cu, Zn, Li, K,
and Na, and Q is at least one member of the group consisting of Ba,
Ca and Sr, the total content of M, Q and Bi is equal to or greater
than 3 molar parts when the total content of Ti and Zr is 100 molar
parts, and the crystal particle size of said dielectric ceramic is
30 nm or more and 150 nm or less.
12. The dielectric ceramic according to claim 11, wherein the total
content of M, Q and Bi is equal to or less than 12 molar parts when
the total content of Ti and Zr is 100 molar parts.
13. The dielectric ceramic according to claim 12, wherein M is
absent.
14. The dielectric ceramic according to claim 12, wherein Q is
absent.
15. The dielectric ceramic according to claim 14, wherein none of
the Ba and Ti are substituted.
16. The dielectric ceramic according to claim 11, wherein M is
absent.
17. The dielectric ceramic according to claim 11, wherein Q is
absent.
18. The dielectric ceramic according to claim 17, wherein none of
the Ba and Ti are substituted.
19. In a method of forming a multilayer ceramic capacitor
comprising forming a ceramic green sheet from a slurry of a
dielectric ceramic, forming a laminate comprising a plurality of
the ceramic green sheets with a pair of internal electrodes
disposed at different interfaces between adjacent ceramic green
sheets, and sintering the laminate, the improvement which comprises
the dielectric being a dielectric ceramic according to claim
11.
20. In a method of forming a multilayer ceramic capacitor
comprising forming a ceramic green sheet from a slurry of a
dielectric ceramic, forming a laminate comprising a plurality of
the ceramic green sheets with a pair of internal electrodes
disposed at different interfaces between adjacent ceramic green
sheets, and sintering the laminate, the improvement which comprises
the dielectric being a dielectric ceramic according to claim 12.
Description
[0001] This is a continuation of application Ser. No.
PCT/JP2012/056688, filed Mar. 15, 2012, the entire contents of
which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a multilayer ceramic
capacitor, and also relates to a dielectric ceramic used for the
multilayer ceramic capacitor, a multilayer ceramic electronic
component represented by the multilayer ceramic capacitor, and a
method for manufacturing the multilayer ceramic capacitor.
BACKGROUND ART
[0003] With reference to FIG. 1, a multilayer ceramic capacitor 1
that is a representative example of a multilayer ceramic electronic
component according to the present invention will be described
first.
[0004] Multilayer ceramic capacitor 1 includes a multilayer body 2
which is formed of a plurality of laminated ceramic layers 3 and a
plurality of internal electrodes 4 and 5 each formed along an
interface between ceramic layers 3.
[0005] A first external electrode 8 and a second external electrode
9 are formed at mutually different positions on an outer surface of
multilayer body 2. In the multilayer ceramic capacitor 1
illustrated in FIG. 1, first external electrode 8 and second
external electrode 9 are formed respectively on opposing end
surfaces 6 and 7 of multilayer body 2. Internal electrode 4
includes a plurality of first internal electrodes 4 which are
electrically connected to first external electrode 8, and internal
electrode 5 includes a plurality of second internal electrodes 5
which are electrically connected to second external electrode 9.
First internal electrodes 4 and second internal electrodes 5 are
disposed alternately in the lamination direction. If necessary, a
surface of external electrode 8 is coated with a first plating
layer 10 and a second plating layer 12, while a surface of external
electrode 9 is coated with a first plating layer 11 and a second
plating layer 13.
[0006] Since size reduction is particularly required for the
multilayer ceramic capacitor, the process of manufacturing the
multilayer ceramic capacitor includes a method of laminating a
green sheet made of a dielectric ceramic and an internal electrode
layer and then sintering the laminated sheet and layer at the same
time. For cost reduction, base metals such as Ni are used for an
internal electrode of the multilayer ceramic capacitor.
[0007] In recent years, as thinning of the ceramic layer has
further progressed, thinning of the internal electrode is also
urgently required. However, thinning of the internal electrode
causes a problem that the rate of coverage of the internal
electrode tends to be decreased due to spherically-agglomerated
metal particles. This requires sintering at a lower
temperature.
[0008] Furthermore, since a multilayer ceramic electronic component
is required to have various characteristics, it also becomes
necessary to use various types of metals such as Ag and Cu as a
metal for an internal electrode. This also requires sintering at a
low temperature.
[0009] For the reasons as described above, a ceramic material that
can be sintered at a low temperature and exhibits excellent
dielectric properties is demanded.
[0010] For example, PTD 1 discloses a barium titanate-based
dielectric ceramic composition suitable for a multilayer substrate
or a multilayer ceramic capacitor, and also discloses that the
dielectric ceramic composition can be sintered at 1000.degree. C.
or lower.
CITATION LIST
Patent Document
[0011] PTD 1: Japanese Patent Laying-Open No. 2007-290940
SUMMARY OF INVENTION
Technical Problem
[0012] In the dielectric ceramic composition in PTD 1, however,
there is a problem that the specific resistance at a high
temperature (150.degree. C.) is relatively low.
[0013] Thus, an object of the present invention is to provide a
dielectric ceramic that can be sintered at a sufficiently low
temperature and has a high specific resistance at a high
temperature, and also to provide a multilayer ceramic electronic
component (a multilayer ceramic capacitor, a multilayer ceramic
substrate, and the like) made using the dielectric ceramic.
Solution to Problem
[0014] As the solution to the problems noted, a multilayer ceramic
capacitor of the present invention includes a multilayer body
having a plurality of laminated dielectric ceramic layers and a
plurality of internal electrodes formed along interfaces between
the dielectric ceramic layers; and an external electrode formed on
an outer surface of the multilayer body. The composition of the
multilayer body includes a perovskite-type compound containing Ba
and Ti (where a part of Ba may be substituted by Ca, and a part of
Ti may be substituted by Zr) as a primary ingredient, and further
includes M (where M is at least one of Cu, Zn, Li, K, and Na) and
Bi. A total content of M and Bi is equal to or greater than 3 molar
parts when a total content of Ti and Zr is 100 molar parts. The
size of each of the dielectric ceramic is 30 nm or more and 150 nm
or less.
[0015] In this case, it is preferable that the composition of the
multilayer body satisfies the condition that the total content of M
and Bi is equal to or less than 12 molar parts when the total
content of Ti and Zr is 100 molar parts.
[0016] Furthermore, a multilayer ceramic capacitor of the present
invention includes a multilayer body having a plurality of
laminated dielectric ceramic layers and a plurality of internal
electrodes formed along interfaces between the dielectric ceramic
layers; and an external electrode formed on an outer surface of the
multilayer body. The composition of the dielectric includes a
perovskite-type compound containing Ba and Ti (where a part of Ba
may be substituted by Ca, and a part of Ti may be substituted by
Zr) as a primary ingredient, and further includes Q (where Q is at
least one of Ba, Ca and Sr) and Bi. The total content of Ba, Ca,
Sr, and Bi is equal to or greater than 3 molar parts when the total
content of Ti and Zr is 100 molar parts. The crystal particle size
of the dielectric ceramic is 30 nm or more and 150 nm or less.
[0017] In this case, it is preferable that the composition of the
multilayer body satisfies a condition that the total content of Ba,
Ca, Sr, and Bi is equal to or less than 12 molar parts when the
total content of Ti and Zr is 100 molar parts.
[0018] Furthermore, a multilayer ceramic capacitor of the present
invention includes a multilayer body having a plurality of
laminated dielectric ceramic layers and a plurality of internal
electrodes formed along interfaces between the dielectric ceramic
layers; and an external electrode formed on an outer surface of the
multilayer body. the composition of the dielectric includes a
perovskite-type compound containing Ba and Ti (where a part of Ba
may be substituted by Ca, and a part of Ti may be substituted by
Zr) as a primary ingredient, and further includes M (where M is at
least one of Cu, Zn, Li, K, and Na) and Bi. The crystal particle
size of the dielectric ceramic is 30 nm or more and 150 nm or less.
The total content of M and Bi is equal to or greater than 3 molar
parts when the total content of Ti and Zr at a time when the
multilayer body is dissolved in a solvent is 100 molar parts.
[0019] In this case, it is preferable that the total content of M
and Bi is equal to or less than 12 molar parts when the total
content of Ti and Zr at a time when the multilayer body is
dissolved in the solvent is 100 molar parts.
[0020] Furthermore, a dielectric ceramic of the present invention
includes a perovskite-type compound containing Ba and Ti (where a
part of Ba may be substituted by Ca, and a part of Ti may be
substituted by Zr) as a primary ingredient, and further includes M
(where M is at least one of Cu, Zn, Li, K, and Na) and Bi. The
total content of M and Bi is equal to or greater than 3 molar parts
when the total content of Ti and Zr is 100 molar parts. The crystal
particle size of the dielectric ceramic is 30 nm or more and 150 nm
or less.
[0021] In this case, it is preferable that the total content of M
and Bi is equal to or less than 12 molar parts when the total
content of Ti and Zr is 100 molar parts.
[0022] Furthermore, a dielectric ceramic according to the present
invention includes a perovskite-type compound containing Ba and Ti
(where a part of Ti may be substituted by Zr) as a primary
ingredient, and further includes Q (where Q is at least one of Ba,
Ca and Sr) and Bi. The total content of Ba, Ca, Sr, and Bi is equal
to or greater than 3 molar parts when the total content of Ti and
Zr is 100 molar parts. The crystal particle size of the dielectric
ceramic is 30 nm or more and 150 nm or less.
[0023] In this case, it is preferable that the total content of Ba,
Ca, Sr, and Bi is equal to or less than 12 molar parts when the
total content of Ti and Zr is 100 molar parts.
[0024] The dielectric ceramic of the present invention described
above can be used for a dielectric ceramic layer of a multilayer
ceramic electronic component including a multilayer body having a
plurality of laminated dielectric ceramic layers and a plurality of
internal electrodes formed along interfaces between the ceramic
layers; and external electrodes formed on an outer surface of the
multilayer body.
[0025] Furthermore, a method for manufacturing a multilayer ceramic
capacitor of the present invention includes the steps of: preparing
primary ingredient powder including a perovskite-type compound
containing Ba and Ti (where a part of Ba may be substituted by Ca,
and a part of Ti may be substituted by Zr) as a primary ingredient;
preparing at least one compound of M and Q (where M is at least one
of Cu, Zn, Li, K, and Na, and Q is at least one of Ba, Ca and Sr),
and a Bi compound; blending the primary ingredient powder, the at
least one compound of M and Q, and the Bi compound, and obtaining a
ceramic slurry; obtaining a ceramic green sheet from the ceramic
slurry; laminating the ceramic green sheets and internal electrode
layers to obtain a non-sintered multilayer body; and sintering the
non-sintered multilayer body to obtain a multilayer body having an
internal electrodes formed between dielectric ceramic layers. The
total content of M, Q and Bi is equal to or greater than 3 molar
parts when the total content of Ti and Zr is 100 molar parts. The
crystal particle size of each of the dielectric ceramic layers is
30 nm or more and 150 nm or less.
[0026] In this case, it is preferable that the total content of M,
Q and Bi is equal to or less than 12 molar parts when the total
content of Ti and Zr is 100 molar parts.
Advantageous Effects of Invention
[0027] According to the present invention, it becomes possible to
provide a dielectric ceramic that can be sintered at a sufficiently
low temperature and has a high specific resistance at a high
temperature, and thereby significantly contribute to size reduction
and enhanced performance of a multilayer ceramic electronic
component (a multilayer ceramic capacitor, a multilayer ceramic
substrate, and the like).
BRIEF DESCRIPTION OF DRAWINGS
[0028] FIG. 1 is a schematic diagram showing an example of a
multilayer ceramic capacitor representative of a multilayer ceramic
electronic component of the present invention.
DESCRIPTION OF EMBODIMENTS
[0029] The dielectric ceramic of the present invention includes a
perovskite-type compound containing Ba and Ti (where a part of Ba
may be substituted by Ca, and a part of Ti may be substituted by
Zr) as a primary ingredient, and further includes M (where M is at
least one of Cu, Zn, Li, K, and Na) and Bi. Also, the total content
of M and Bi relative to 100 molar parts of the total content of Ti
and Zr is equal to or greater than 3 molar parts, and the crystal
particle size of the dielectric ceramic is 30 nm or more and 150 nm
or less, so that both of sintering at a low temperature and an
increased specific resistance at a high temperature can be
achieved.
[0030] In this case, although the upper limit value of the total
content of M and Bi relative to 100 molar parts of the total
content of Ti and Zr is not particularly defined, the effect of the
present invention becomes remarkable particularly at 12 molar parts
or lower.
[0031] Furthermore, another dielectric ceramic of the present
invention includes a perovskite-type compound containing Ba and Ti
(where a part of Ba may be substituted by Ca, and a part of Ti may
be substituted by Zr) as a primary ingredient, and also includes Q
(where Q is at least one of Ba, Ca and Sr) and Bi. Also, the total
content of Ba, Ca, Sr, and Bi is equal to or greater than 3 molar
parts when the total content of Ti and Zr is 100 molar parts, and
the crystal particle size of the dielectric ceramic is 30 nm or
more and 150 nm or less, so that both of sintering at a low
temperature and an increased specific resistance at a high
temperature can be achieved.
[0032] In this case, although the upper limit value of the total
content of Ba, Ca, Sr, and Bi at the time when the total content of
Ti and Zr is 100 molar parts is not particularly defined, the
effect of the present invention becomes remarkable particularly at
12 molar parts or lower.
[0033] In addition, while the molar ratio of a Ba site (Ba, Ca, Sr)
and a Ti site (Ti, Zr) in the primary ingredient is basically close
to 1, this molar ratio can be controlled to fall within a range of
0.97 or more and 1.05 or less as long as it does not affect the
object of the present invention.
[0034] Furthermore, as long as it does not affect the object of the
present invention, the dielectric ceramic of the present invention
may contain a rare earth element, Mg, Mn, V, Al, Ni, Co, Zn or the
like.
[0035] Hereinafter, an example of a method for manufacturing the
dielectric ceramic of the present invention will be described.
[0036] First, a hydrothermal synthesis method is used to prepare
particulate powder of barium titanate, which is then calcined to
obtain primary ingredient powder. Although the hydrothermal
synthesis method is suitable for obtaining the particulate raw
material powder, a solid-phase synthesis method may also be
used.
[0037] Then, powders of CuO, ZnO, BaCO.sub.3, SrCO.sub.3,
CaCO.sub.3, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3, K.sub.2CO.sub.3,
and Bi.sub.2O.sub.3 are added into the primary ingredient powder at
a predetermined amount.
[0038] As long as it does not affect the object of the present
invention, the powders need not be limited to oxide powder or
carbonate powder. The powders are blended in a solution and dried,
thereby obtaining ceramic raw material powder as a final raw
material.
[0039] The subsequent processes will be described by taking, as an
example, a multilayer ceramic capacitor representing a multilayer
ceramic electronic component of the present invention.
[0040] The above-mentioned ceramic raw material powder is prepared.
The ceramic raw material powder is blended, where necessary, with
an organic binder component in a solvent to provide a ceramic
slurry. Then, the ceramic slurry is formed into a sheet, thereby
obtaining a ceramic green sheet.
[0041] Next, a conductor film serving as an internal electrode is
formed on the ceramic green sheet, which formation can be conducted
according to several methods. Among them, one simple method is to
screen-print a paste containing metal particles such as Ag and Ni
and an organic vehicle into a desired pattern. Alternatively, there
is also a method of forming a conductor film according to a metal
foil transfer-printing method, or forming a conductor film while
masking it by the vacuum thin-film deposition method such as the
sputtering method.
[0042] In this way, ceramic green sheets and internal electrode
layers are laminated to form multiple layers, and then
pressure-bonded, thereby obtaining a raw multilayer body before
sintering.
[0043] This raw multilayer body is held, for example, for 6 hours
at a temperature of 280.degree. C. under an air atmosphere, thereby
burning off the binder. Then, in a sintering furnace, the
multilayer body is sintered at a predetermined temperature under a
predetermined atmosphere, for example, at a temperature
rising/falling rate of 20.degree. C./minutes at a maximum
temperature of 700 to 900.degree. C. under an air atmosphere, to
obtain a ceramic multilayer body including a sintered ceramic
body.
[0044] A multilayer ceramic capacitor is obtained by forming
external electrodes at locations where the internal electrode are
drawn out of the ceramic multilayer body.
[0045] Examples of a method of forming the external electrode may
include a method of applying a paste containing glass frit and
metal particles of Cu, Ag and the like on the ceramic multilayer
body and baking it thereafter, a method of applying a resin
electrode containing a thermosetting resin and an epoxy resin and
curing it thereafter, and the like. If necessary, a plating layer
of Ni, Sn or the like is further formed on the surface of the
external electrode.
[0046] The multilayer ceramic electronic component of the present
invention is applicable not only to a multilayer ceramic capacitor
but also to various electronic components such as a multilayer
ceramic substrate and the like.
Experimental Example
[0047] First, a particulate powder of barium titanate was produced
using the hydrothermal synthesis method, and then calcined to
obtain primary ingredient powder having a prescribed average
particle size.
[0048] Specifically, powders of Ba(OH).sub.2, Ca(OH).sub.2,
Sr(OH).sub.2, TiO.sub.2, and ZrO.sub.2 were first prepared as
materials constituting a primary ingredient.
[0049] Then, amounts of the TiO.sub.2 and ZrO.sub.2 were weighed
such that content of each of Ti and Zr relative to 1 molar part of
the total content of Ti and Zr was equal to the molar part shown in
each of Tables 1 and 2, and stirred in the water as a medium. Then,
Ba(OH).sub.2, Ca(OH).sub.2 and Sr(OH).sub.2 were weighed such that
each content of Ba, Ca and Sr relative to 1 molar part of the total
content of Ti and Zr is equal to the molar part shown in each of
Tables 1 and 2, and then introduced.
[0050] The temperature was raised to 200.degree. C. while applying
pressure so as not to evaporate the aqueous medium in which
materials constituting the primary ingredient were distributed.
Thereby, a reaction is caused to proceed. Consequently, a powder
with an average particle size of about 20 nm was obtained in the
aqueous medium.
[0051] Then, the obtained powder was dried and calcined, thereby
obtaining ceramic powder that was primary ingredient powder. In
this case, the pre-sintering temperature was changed in the range
from 900 to 1100.degree. C., to change the average particle size of
the primary ingredient powder.
[0052] As a sub-ingredient, powders of CuO, ZnO, BaCO.sub.3,
SrCO.sub.3, CaCO.sub.3, Li.sub.2CO.sub.3, Na.sub.2CO.sub.3,
K.sub.2CO.sub.3, and Bi.sub.2O.sub.3 were weighed such that content
of each of Bi, Cu, Zn, Ba, Sr, Ca, Li, Na, and K relative to 100
molar parts of the total content of Ti and Zr in the
above-described primary ingredient was equal to the molar part
shown in each of Tables 1 and 2. The weighed powders were then
blended into the primary ingredient powder to obtain a powder
mixture.
[0053] The obtained powder mixture was confirmed to have the
composition almost identical to those shown in Tables 1 and 2
through ICP emission spectrochemical analysis.
[0054] Subsequently, a polyvinyl butyral-based organic binder was
added and blended into the above-described powder mixture, to which
an organic solvent containing toluene was added, and the mixture
was wet-blended using a ball mill for 24 hours to provide a ceramic
slurry.
[0055] The ceramic slurry was formed into a sheet to obtain a
ceramic green sheet having a thickness of 10 .mu.m.
[0056] Then, a plurality of these ceramic green sheets were
laminated, and pressure-bonded to obtain a raw multilayer body
having a size of 4 mm.times.4 mm.times.0.5 mm.
[0057] This raw multilayer body was heated at 280.degree. C. under
an air atmosphere to remove an organic binder. Then, the multilayer
body was sintered at 800.degree. C. under an air atmosphere. When
the resultant sintered multilayer body (sintered body) was
dissolved in a solvent and subjected to ICP emission
spectrochemical analysis, this multilayer body was confirmed to
have a composition almost identical to those shown in Tables 1 and
2.
[0058] A resin electrode containing Ag and an epoxy resin was
applied to both main surfaces of the obtained sintered body and
cured at 180.degree. C., thereby producing a specimen for
evaluation.
[0059] The capacitance of the obtained specimen was measured using
an automatic bridge-type meter under the condition of 25.degree.
C., 1 kHz and 1.0 Vrms, to calculate the dielectric constant from
the dimensions of the sintered body. Ten specimens were subjected
to measurement to calculate an average value.
[0060] Then, the resistance after applying a voltage of 500V for 60
seconds at 150.degree. C. was measured, and the specific resistance
was calculated from the dimensions of the sintered body. Ten
specimens were subjected to measurement to calculate an average
value.
[0061] The fracture surface of each specimen was observed with a
scanning electron microscope (SEM). Then, through image analysis,
the particle size of the crystal particle was measured based on the
equivalent circle diameter of the crystal particle as a particle
size. The particle sizes of 100 crystal particles for each specimen
were measured and the average value was calculated as a crystal
particle size.
[0062] Tables 1 and 2 each show the average crystal particle size,
dielectric constant and specific resistance results in each
specimen. Note that the content of each element relative to 100
molar parts of the primary ingredient is shown in the column of the
sub-ingredient.
TABLE-US-00001 TABLE 1 Speci- Primary Ingredient Sub-Ingredient
(Molar Part) Crystal Specific men (Molar Part) M Q Total Particle
Dielectric Resistance No. Ba Ca Sr Ti Zr Bi Cu Zn Li Na K Ba Sr Ca
Content Size Constant log p 1 1 1 7 3 10 30 120 7.6 2 1 1 7 3 10 50
300 7.4 3 1 1 7 3 10 100 720 7.5 4 1 1 7 3 10 150 1100 7.3 5 1 1 7
3 10 200 1300 5.8 6 1 1 7 3 10 400 1600 5.8 7 1 1 7 3 10 1000 2200
5.4 8 1 1 9 1 10 150 1060 8.9 9 1 1 9 1 10 200 1220 6.6 10 1 1 5 5
10 150 1100 7.0 11 1 1 5 5 10 200 1300 5.2 12 0.95 0.05 1 7 3 10
130 980 7.9 13 0.98 0.02 1 7 3 10 130 1040 7.8 14 1 0.9 0.1 7 3 10
130 1010 8.2 15 1 1 6 3 9 140 990 7.6 16 1 1 6 3 9 220 1400 5.2 17
1 1 7 5 12 130 920 7.4 18 1 1 7 5 12 190 1220 5.8 19 1 1 6 3 9 130
910 7.5 20 1 1 6 3 9 180 1300 5.9 21 1 1 7 5 12 140 900 7.7 22 1 1
7 5 12 190 1310 6.1 23 1 1 6 4 10 150 1100 7.2 24 1 1 6 4 10 210
1250 5.1 25 1 1 8 2 10 120 890 7.2 26 1 1 8 2 10 280 1210 5.1 27 1
1 7 3 10 120 880 7.1 28 1 1 7 3 10 250 1105 5.2
TABLE-US-00002 TABLE 2 Speci- Primary Ingredient Sub-Ingredient
(Molar Part) Crystal Specific men (Molar Part) M Q Total Particle
Dielectric Resistance No. Ba Ca Sr Ti Zr Bi Cu Zn Li Na K Ba Sr Ca
Content Size Constant log p 29 1 1 0.7 0.3 1.0 110 80 6.0 30 1 1 2
1 3.0 130 910 7.3 31 1 1 3 2 5.0 150 1110 7.2 32 1 1 0.7 0.3 1.0
100 60 5.7 33 1 1 2 1 3.0 130 880 7.8 34 1 1 3 2 5.0 150 1088 7.6
35 1 1 0.7 0.3 1.0 110 60 5.8 36 1 1 2 1.0 3.0 130 820 7.2 37 1 1 3
2.0 5.0 150 1046 7.1
[0063] Specimen numbers 1 to 28 in Table 1 each show effects
obtained by changing the type, the content and the crystal particle
size of each sub-ingredient.
[0064] Specimen numbers 29 to 37 in Table 2 each show effects
obtained by changing the type and the content of each
sub-ingredient.
[0065] According to the results in Tables 1 and 2, a specific
resistance log p at 150.degree. C. was as high as 7 or higher while
the dielectric constant was also 100 or higher in the case of a
specimen of a dielectric ceramic including a perovskite-type
compound containing Ba and Ti (where a part of Ba may be
substituted by Ca, and a part of Ti may be substituted by Zr) as a
primary ingredient, and further including M (where M is at least
one of Cu, Zn, Li, K, and Na) and Bi, in which the crystal particle
size of the ceramic is 30 nm or more and 150 nm or less, and the
total content of M and Bi relative to 100 molar parts of the total
content of Ti and Zr is equal to or greater than 3 molar parts.
Also, specific resistance log p at 150.degree. C. was as high as 7
or higher while the dielectric constant was also 100 or higher in
the case of a specimen of a dielectric ceramic including a
perovskite-type compound containing Ba and Ti (where a part of Ba
may be substituted by Ca, and a part of Ti may be substituted by
Zr) as a primary ingredient, and further including Q (where Q is at
least one of Ba, Ca and Sr) and Bi, in which the crystal particle
size of the ceramic is 30 nm or more and 150 nm or less, and the
total content of Ba, Ca, Sr, and Bi is equal to or greater than 3
molar parts when the total content of Ti and Zr is 100 molar
parts.
INDUSTRIAL APPLICABILITY
[0066] The dielectric ceramic of the present invention can be
applied to a multilayer ceramic electronic component, and
particularly to a multilayer ceramic capacitor, a multilayer
ceramic substrate and the like, and contributes to size reduction
and increased performance of these components.
REFERENCE SIGNS LIST
[0067] 1 multilayer ceramic capacitor,
[0068] 2 multilayer body,
[0069] 3 ceramic layer,
[0070] 4, 5 internal electrode,
[0071] 6, 7 end surface,
[0072] 8, 9 external electrode,
[0073] 10, 11 first plating layer,
[0074] 12, 13 second plating layer.
* * * * *